Adds native authentication to serverless and ECH comparison

Adding native authentication to the ECH and serverless comparison table

Author: eedugon

deploy-manage/deploy/elastic-cloud/differences-from-other-elasticsearch-offerings.md

@@ -137,13 +137,14 @@ This table compares Security capabilities between {{ech}} deployments and Server
 |---------|---------------------|------------------------------|------------------|
 | **[Advanced Entity Analytics](/solutions/security/advanced-entity-analytics.md)** | ✅ | ✅ | |
 | **[AI Assistant](/solutions/security/ai/ai-assistant.md)** | ✅ | ✅ | |
-| **API keys** | ✅ | ✅ | |
+| **[API keys](/deploy-manage/api-keys.md)** | ✅ | ✅ | |
 | **[Cloud Security](/solutions/security/cloud.md)** | ✅ | ✅ | |
 | [**Defend for Containers integration**](https://www.elastic.co/guide/en/security/8.18/d4c-overview.html) | ✅ (deprecated in 9.0) | ❌ | Not available in Serverless |
 | **[Endpoint security](/solutions/security/configure-elastic-defend.md)** | ✅ | ✅ | |
 | **[Kibana Alerts](/deploy-manage/monitor/monitoring-data/configure-stack-monitoring-alerts.md)** | ✅ | ✅ | |
 | **Kibana navigation** | Standard layout | Different layout | UI differences in Security projects |
 | **[LogsDB](/manage-data/data-store/data-streams/logs-data-stream.md)** | Optional | ✅ | - Enabled by default <br>- Cannot be disabled |
+| **[Native realm authentication](/deploy-manage/users-roles/cluster-or-deployment-auth/native.md)** | ✅ | ❌ | Only API keys based authentication supported |
 | **Role-based access control** | ✅ | Limited | Core RBAC functionality supported |
 | **SIEM capabilities** | ✅ | ✅ | Core functionality supported |